i noticed that my baby royals all got really green from when i moved them from my dim bedroom to the kitchen. lighter substrate as well...but i think the sun is def good for them
the tank gets indirect light for most of the day. However it's not enough light for algae to grow or at least compete with the fish eating it. However i did notice a change with going bare bottom (used to have old amazonia as my substrate) that they showed more color or pattern